This application incorporates by reference of Taiwan application Serial No. 90213347, Filed Aug. 6, 2001.
1. Field of the Invention
The invention relates in general to a power supply system, and more particularly to a power supply system having standby power.
2. Description of the Related Art
Formerly, there is only one main power regulator in the power supply and the power supply therefore has to be switched on for supplying power to the computer over a long period of time. Since Intel develops the standard ATX, which is the modern-day shape and layout of PC motherboards, in 1995, the power supply of the ATX motherboard requires two power regulators, that is, adding a standby power regulator.
The traditional power supply provides one output for main power and the other output for standby power. The main power circuit requires a switching regulator for outputting DC (Direct Current) power at +12V, +5V, and +3.3V while the standby power circuit requires another switching regulator for outputting DC power at +5V during power-off.
Referring to FIG. 1, a block diagram of a traditional power supply for generating the power required by the memory system is illustrated. Suspend-to-RAM (STR) occurs when a system detects that most of the applications or system components are under silent operation and enters a low-power state. While in the low power (STR) state, memory system 101 remains powered to retain the system information while most other components turn off to conserve energy. The traditional power supply with standard ATX includes a main power regulator 10 and a standby power regulator 11. When the motherboard supports STR, either the main power regulator 10 or the standby power regulator 11 generates power for the memory system 101. In the normal state, the MOS (Metal Oxide Semiconductor) switch 103 receives switch signal SW1 and becomes open. The main power regulator 10 then provides the memory system 101 with main power MP. In the STR state, the MOS switch 105 receives switch signal SW2 and becomes open. The standby power regulator 11 then provides the memory system 101 with standby power SP. The power supply stops providing any power while the computer shuts down.
Referring to FIG. 2, a block diagram of a traditional power supply system with standard ATX is shown. The alternating current source 201 outputs alternating current power signal AC to the main power regulator 10 and the standby power regulator 11. The main power regulator 10 includes switching controller 203, MOS switch 205, multiple transformer 207, +12V rectifier 208, +5V rectifier 209 and +3.3V rectifier 210. The +12V rectifier 208, +5V rectifier 209 and +3.3V rectifier 210 individually output the voltage signal (or voltage) Out12V, Out5V, and Out3.3V for providing power at +12V, +5V, and +3.3V. The standby power regulator 11 includes switching controller 213, MOS switch 215, transformer 217, +5V rectifier 219. The +5VBS rectifier 219 outputs the standby voltage signal Out5VSB for providing standby power at +5V. The voltage signal Out5V outputted by the +5V rectifier 209 for the main power regulator 10 has the same electric potential with the standby voltage signal Out5VBS outputted by the +5VBS rectifier 219 for the standby power regulator 11. However, the +5V rectifier 209 and +5VBS rectifier 219 belong to different power regulators without electrical connection and therefore it leads to a waste and an unsteady effect for the power regulation.
It is therefore an object of the invention to provide a power supply system with a simplified structure for the regulators. It reduces the cost and minimizes the whole volume under compatibility and even more reliable and stable for power regulation.
The invention achieves the above-identified objects by providing a power supply system for generating main power and standby power to be applied to a computer that produces a PSON (Power Supply ON) signal. The power supply system includes a main power regulator, standby power regulator, and automatic electronic switch. The main power regulator having a first rectifier outputs a first voltage signal to provide main power. The standby power regulator having a second rectifier outputs a standby voltage signal to provide standby power to the computer when the PSON signal is not produced. The automatic electronic switch receives the standby voltage signal in response to a the PSON signal and outputs a second voltage signal to provide further main power to the computer.